1. Field of the Invention
The present invention relates to an irradiation device, especially for the cosmetic, diagnostic and therapeutic application of light, comprising an incoherent light source and a reflector which surrounds the light source and has an opening in the radiation direction of the light source, from which opening the radiation emerges.
2. Description of the Related Art
The therapeutic effect of light has long been known. Various devices that operate in selected spectral ranges are known for various medical syndromes.
DE 40 08 098 discloses a rod-shaped luminaire surrounded axially by a reflector, which has a slit-like opening for the output of light. The opening extends parallel to the longitudinal axis of the luminaire and is formed by the legs of the reflector running toward each other. At their ends, following the nearest approach of the legs to a radius smaller than the curvature radius of the reflector, these legs are bent counter to this curvature. As a result, increased radiation density is attained.
DE-AS 17 64 685 discloses an electric all-purpose discharge lamp with a light-permeable bulb, an electrode pair connectable to a voltage source, an ionizable filling and a covering of luminous substance applied to the bulb inner wall. This lamp produces an output of 6 to 50 .mu./W per lumen of visible light in the range above 290 nm wave length, particularly for the middle ultraviolet range, and an output of 150 to 700 .mu./W per lumen of visible light for the near ultra violet range. The output in these two ranges is said to be in the ratio of 1:8 to approximately 1:40. It is also stated that the total radiation per lumen is to have roughly the same share as natural daylight of corresponding color temperature. Apart from the fact that the output comparison in 1 m/W is misleading and that non-visible light is being compared to visible light, it can be calculated that a maximum output of 1.5 mW should be emitted for the total range of 290 to 320 nm and a maximum output of 42 mW for the range of 320 to 380. No area reference is given. Further, it is disclosed that lamps of this type can have different maximums into the range of 700 nm, e.g., 570 to 595 or 595 to 625. Overall, the document also discusses prior art related to luminous substance lamps of special wave length, which can have, in contrast to daylight, a sharper maximum at different wave lengths. Suitable luminous substance mixtures are indicated for this purpose, including characteristic metal combinations for different color temperatures. Along with the aforementioned special ratios in the range of UV light, various outputs of natural light compared to selected artificial lamps are shown for lamps with a 40 W rated output and a light output of 2100 to 2300 lm. The goal of that invention is to propose a lamp that, in an 8-hour workday, avoids undesired reddening of the skin (analogous to sunburn) but nonetheless has a desired color reproduction effect. Different biological effects are also mentioned in tabular form, specifically, the effect of light on eye pigmentation, the effect on pineal and gonadal glands of radiation in the wavelength range of 380 to 700 nm, and the bacteria-killing effect of UV light at the 254 nm wavelength. For the UV range, in particular, the formation of vitamins, the de-activation of microorganisms and the cosmetic effect are mentioned. It is also noted that UV radiation can cause changes in the amounts of melanin in the skin. However, this effect is ascribed specifically to the effect of light of the wavelength 290 to 320 nm. It is therefore emphasized that, for this range, less radiation should be provided by the all-purpose lamp with a natural daylight spectrum according to the invention.
DE 31 21 689 C2 proposes a luminous substance lamp that filters by means of the bulb in the UVC and UVB range. The document states that for the UVA range, specifically, a maximum above 350 nm with a spectral width of approximately 320 to 400 nm exists and, in addition, a marked radiation emission in the orange-red range occurs at roughly 650 nm. The intended result is for the luminous substance lamps generally used in solariums (DE OS 26 2B 091) for tanning or for treatment of psoriasis to produce no side effects, such as fatigue or reduced activity. The orange range is meant to have a unilateral influence on nerve tonus and to result in vessel expansion to prevent fatigue. However, the document states that lamps of this type have, in the ranges of 404 and 437 nm (blue), a maximum emission typical of quicksilver and that it is therefore not possible to filter out the blue range as desired according to the description.
DE OS 34 31 692 proposes that a sunlight-like luminous substance lamp with five energy maximums of roughly 320, 380, 450, 550, 650 nm be used. Said energy maximums are to be attained by lamps suitably doped with a mixture of the specified luminous substances. The document notes that cell damage is reparable and eye regeneration is possible in the UVA range, while in the range below 320 nm, long-wave UVB radiation lead to the formation of vitamin D3, calcium resorption, metabolic activation and increased performance of the muscle system and circulatory organs. The document further states that sunburn effects occur only in conjunction with wavelength ranges below 300 nm. For the 300 to 400 nm range, spectral emissions roughly similar to those in the previously cited DE AS 17 64 685 are specified.
In many documents, suitable doping metals are specified for various radiation ranges, e.g., red to dark red (U.S. Pat. No. 3,287,586) or blue (DE OS 19 22 416). Special lamps (DD 201 207 and DD 221 374) have been designed for therapeutic windows around the 325 nm wavelength. DE OS 32 39 417 proposes phosphorous doping for optimized emissions at 340-400 nm for the treatment of skin ailments.
DE 29 10 468 A1 proposes a UV luminous substance radiation source for photobiological and photochemical purposes, particularly for tanning irradiation, wherein the bulb of the radiation source is in contact with a fluid layer, preferably a water layer or water bath. Such a water bath can also be embodied as a water bed with couch, whereby the projection area is a flexible transparent cover of the water bed and the water temperature is set at 30 to 50.degree. C., preferably 35 to 40.degree. C. The document proposes, in detail, an arrangement of the individual radiation sources, which are disposed in gutter-like water containers that surround the luminous substance tubes. The gutter-like elements are equipped with reflectors on the side opposite to the radiation object for the purpose of permitting light reflection from the cooling device toward the projection surface. Also proposed is the use of UV luminous substance lamps in the 300 to 430 nm spectrum with luminous substances that cannot be highly loaded thermally; as applicable, additives are added to the cooling water to influence the spectral transmission grade and/or the reduction in the electrical conductivity. The attainable pigmentation-active radiation output, i.e., the irradiation output, in the aforementioned UV range is put at approximately 140 W/m.sup.2. Optionally, this irradiation device is also suitable for medical applications (diagnoses and therapy), particularly for the treatment of skin diseases and skin damage. However, the device did not succeed because its main purpose, tanning, can be attained more cheaply with solariums of the traditional type and because the device is too cumbersome and expensive for medical practice. A main reason for this may be that very high demands are placed on the lamps, since the lamp surface temperature of 35 to 40.degree. C., particularly at the relatively high rated output of 115 W, reduces lamp useful life.
It is common to all these devices that the radiation density emitted by them is too low. This leads either to unacceptably long treatment times or to no therapeutic effect at all, since in part the therapeutic effect begins only at a certain radiation density.
A further disadvantage is that for certain spectral ranges (e.g., yellow), there are no suitable doping agents with which suitable radiation densities can be attained. If an attempt is made, by means of suitable filters, to have a broadband light source radiate selectively in these ranges, then the radiation density is further reduced by the filter.
In applications that require high radiation density, it therefore continues to be necessary to use expensive and awkward lasers. The use of different wavelengths after one another, in particular, entails great difficulties with lasers.
From U.S. Pat. No. 5,405,368 a generic device with an incoherent light source is known. The light source is sealed by a glass cylinder and a reflector is arranged around the light source. The cross-section of the reflector is shaped like an ellipse, and the light source is arranged in a focal point of the ellipse. On the side opposite the light source, the reflector has an opening. In front of the opening is arranged a set of optical filters and an iris aperture. A photoflash light is suggested, for example, as the light source. When the device is placed on the body part to be treated, this body part is located at the second focal point of the ellipse. Alternatively, it is suggested that the reflector be designed parabolically and round in cross-section. The iris aperture controls the length and width of the irradiated area, and the maximum length is limited by the length of the light source. Given a proposed lamp length of 8 cm, however, only 5 cm in the center of the lamp is used, whereby approximately uniform radiation occurs. By closing the iris aperture, the length of the irradiated surface can be shortened to a length of 1 mm, as can the width. Given a width of b=5 mm, the width can be shortened by as much as 1 mm by closing the iris aperture. This corresponds to a maximum opening width "d" of one fifth of the diameter. As a result, energy densities in the range of 30 to 100 J/cm.sup.2 are attainable. When an optical band pass in the range of 500 to 650 nm is used, the energy density is reduced by 80%, so that energy densities of 6 to 20 J/cm.sup.2 are still achieved on the skin.
It is disadvantageous in the known device that the useful life of the optical filter is very short, due to the energy densities, and that the relevant manufacturers do not guarantee functional ability. At the same time, the maximum energy densities attainable are not great enough for the applications "desiccation of veins" and "destroying tatoo pigments."